From 103c65a4d188cad6d4c983ed7a5b65939389ed4b Mon Sep 17 00:00:00 2001
From: Sichen <sl10445@nyu.edu>
Date: Mon, 28 Sep 2026 05:32:29 +0000
Subject: [PATCH] grep: separate context groups across files

Track whether a previous file printed a context group so the first group
in a later file receives a separator. Within a file, continue to
separate only groups with a gap between their printed lines.

Cover the default, disabled and custom separators, including recursive
searches across two directories.
---
 src/searcher.rs    | 12 ++++---
 tests/test_grep.rs | 80 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+), 4 deletions(-)

diff --git a/src/searcher.rs b/src/searcher.rs
index 8a17223..3eca035 100644
--- a/src/searcher.rs
+++ b/src/searcher.rs
@@ -26,6 +26,8 @@ pub struct Searcher<'a> {
     any_match: bool,
     had_error: bool,
     binary_notice_enabled: bool,
+    /// Whether a context group was printed by any file in this search.
+    any_group_seen: bool,
 
     // Per-session state
     session_context_buf: ContextBuffer,
@@ -52,6 +54,7 @@ impl<'a> Searcher<'a> {
                 && !config.count
                 && !config.files_with_matches
                 && !config.files_without_match,
+            any_group_seen: false,
 
             session_context_buf: ContextBuffer::new(config.before_context),
             session_match_count: 0,
@@ -671,11 +674,11 @@ impl<'a> Searcher<'a> {
             .map_or(view.line_number, |ctx| ctx.line_number);
 
         // Group separator between non-adjacent groups.
-        // `last_printed_line == 0` means we haven't printed anything yet.
-        //   = first group = skip the separator
+        // `last_printed_line == 0` marks the first group in this file.
+        // Separate it only when a previous file has printed a group.
         if self.config.has_context
-            && last_printed_line > 0
-            && group_start_line > last_printed_line + 1
+            && ((last_printed_line == 0 && self.any_group_seen)
+                || (last_printed_line > 0 && group_start_line > last_printed_line + 1))
         {
             self.writer.write_group_separator()?;
         }
@@ -687,6 +690,7 @@ impl<'a> Searcher<'a> {
 
         self.writer.write_line(view, path)?;
         self.session_last_printed_line = view.line_number;
+        self.any_group_seen = true;
         Ok(())
     }
 
diff --git a/tests/test_grep.rs b/tests/test_grep.rs
index a38d570..c77d0d5 100644
--- a/tests/test_grep.rs
+++ b/tests/test_grep.rs
@@ -1221,6 +1221,86 @@ fn group_separator_behavior() {
         .stdout_only("M\n***\nM\n");
 }
 
+#[test]
+fn context_groups_are_separated_across_files() {
+    let (scene, _) = ucmd();
+    scene.fixtures.write("first", "hit\nno\nno\nhit\n");
+    scene.fixtures.write("second", "hit\n");
+    scene.fixtures.write("b", "hit three\nno\nfar\nhit four\n");
+    scene.fixtures.write("c", "no\nhit five\n");
+    scene.fixtures.write("d", "nothing\n");
+
+    scene
+        .cmd(env!("CARGO_BIN_EXE_grep"))
+        .args(&["-n", "-C0", "hit", "first", "second"])
+        .succeeds()
+        .stdout_only("first:1:hit\n--\nfirst:4:hit\n--\nsecond:1:hit\n");
+
+    scene
+        .cmd(env!("CARGO_BIN_EXE_grep"))
+        .args(&["-n", "-C1", "hit", "b", "c"])
+        .succeeds()
+        .stdout_only("b:1:hit three\nb-2-no\nb-3-far\nb:4:hit four\n--\nc-1-no\nc:2:hit five\n");
+
+    scene
+        .cmd(env!("CARGO_BIN_EXE_grep"))
+        .args(&["-n", "-C0", "hit", "d", "first"])
+        .succeeds()
+        .stdout_only("first:1:hit\n--\nfirst:4:hit\n");
+
+    scene
+        .cmd(env!("CARGO_BIN_EXE_grep"))
+        .args(&["-n", "-C0", "hit", "first", "d", "second"])
+        .succeeds()
+        .stdout_only("first:1:hit\n--\nfirst:4:hit\n--\nsecond:1:hit\n");
+}
+
+#[test]
+fn context_group_separator_options_across_files() {
+    let (scene, _) = ucmd();
+    scene.fixtures.write("first", "hit\nno\nno\nhit\n");
+    scene.fixtures.write("second", "hit\n");
+
+    scene
+        .cmd(env!("CARGO_BIN_EXE_grep"))
+        .args(&[
+            "-n",
+            "-C0",
+            "--no-group-separator",
+            "hit",
+            "first",
+            "second",
+        ])
+        .succeeds()
+        .stdout_only("first:1:hit\nfirst:4:hit\nsecond:1:hit\n");
+
+    scene
+        .cmd(env!("CARGO_BIN_EXE_grep"))
+        .args(&["-n", "-C0", "--group-separator=X", "hit", "first", "second"])
+        .succeeds()
+        .stdout_only("first:1:hit\nX\nfirst:4:hit\nX\nsecond:1:hit\n");
+}
+
+#[test]
+fn recursive_context_groups_are_separated_across_files() {
+    let (scene, mut c) = ucmd();
+    scene.fixtures.mkdir("tree-a");
+    scene.fixtures.mkdir("tree-b");
+    scene.fixtures.write("tree-a/one", "hit\n");
+    scene.fixtures.write("tree-b/two", "hit\n");
+    let first = std::path::Path::new("tree-a").join("one");
+    let second = std::path::Path::new("tree-b").join("two");
+    let expected = format!(
+        "{}:1:hit\n--\n{}:1:hit\n",
+        first.display(),
+        second.display()
+    );
+
+    c.args(&["-r", "-n", "-C0", "hit", "tree-a", "tree-b"])
+        .succeeds()
+        .stdout_only(&expected);
+}
+
 #[test]
 fn adjacent_context_groups_do_not_get_separator() {
     let (_s, mut c) = ucmd();